A properly designed upper IC, lower IC, and MAF pipe should make 10whp. AMS alone has shown a 7whp gain on their LICP. There is power to be made here. Just reducing bends alone can improve spoolup and power. Is WORKS in approval of changing people to a mini battery and different IC pipe setup? Probably not...no offense meant. But many people that use WORKS is because they race in sanction events where mods such as a different battery tray or smaller battery may jump the rules extensively.

Piping is not as cheap to make as you might think. If WORKS came out with an Inhale IC pipe kit would it be worth the price tag? Would people pay it?

 

Your engineering "stand point" is a bit off, so you might want to reread things when you have time.

Two quick points. Shorter IC piping will improve throttle response simply because there is less distance for the air to travel. Second, you might want to research back pressure and turbo charged motors when you have time because the optimum design for a turbo discharge creates no back pressure.

 

hmmm please point me to where I said shorter pipes are not better for throttle response?

I don’t believe I said anything about shorter and longer pipes.

Having shorter pipes does help for sure. However, all the short pipes I have seen touched the battery or the air box. I am against having these pipes touch or rub against any part of the car.

If the outcome of the shorter pipes is to have rubbing then it’s not a good trade off for me.

Also, please in light me on back pressure. Consider me as a noobe and explain to me how cars don’t need back pressure.

 

umm... i've been trying to say that your idea of 'back pressure' is somewhat off.
you said you don't have time to read it.

here it is one last time. as short as i can make it:

back pressure from turbo to intake mani is acutally pressure loss caused by pipe 'friction' effects. this is a load the turbo has to work against.

less back pressure in intake line from turbo = more effective forced induction.

back pressure from exhaust is prectically not needed in a forced induction vehicles. while some back presure is useful for engines, the turbine attached to the exhaust mani more than makes up for it.

pipe friction is a function of pipe diameter and length (along with a number of other things). so a shorter pipe pretty much as the same effect as a bigger (diameter) one. the pressure drop is less sensitve to length however.

the volume of the piping shouldn't be too large 'cos then response goes again. but this is kindda off set by a the benefits above. there's usually a compromise.

if you don't have the time to read this, you really shouldn't have the time to post.

 

First off, cars needing "backpressure" IS A MYTH.

For some extra reading on this, a quick search revealed this:
Backpressure Myth

Basically, the argument is a compromise between flow restriction, length of turbulent flow and throttle response. Also, it's important to mention these two parameters are dependant on the engine RPM.

For example, Engine A has 2 inch IC piping and Engine B has 3 inch piping. If we want to have the same flow rate through these otherwise identical engines, the air has to move at a higher velocity though engine A. Faster moving air will have more frictional losses and thus there will be a pressure drop across the piping. It's likely to achieve this flow rate Engine A will have to make more boost and maybe turn a slightly higher RPM. However, since Engine A has less intake volume, the transient response will be quicker than Engine B.

At higher flow rates Engine B is better at flowing air, but at a midrange or low flow rates Engine A will flow just fine (perhaps better) AND have better throttle response. It's just at the higher flows the flow restriction starts to become a problem.

Let's say we have a tricked out high boost engine. It has to flow lots of air. Let's say it has 4 inch intake piping. When at high boost the air velocity is kept at a reasonable speed and everything flows nicely. But at low flows, the piping seems less like piping and more like a big tank. The throttle response will be worse and the flow will be less like a flow and more like air spewing into a tank. The flow will remain in a turbulent mode for longer until it becomes laminar down the piping.

Basically if the flow is too slow, the length of the turbulent section will be longer than if the flow was moving a little faster to force the flow into a laminar mode sooner. So there will be a balance point where this turbulent flow length and flow restriction will be optimal, but that will only be at one flow rate since the intake diameter is fixed. So if you want good performance up top, but sacrifice a little down low, you will have bigger piping. If you want good performance down lower, but sacrifice performance up top, you will go smaller.

The speeds of the air flowing through the pipes are quite fast. They can get close to sonic speeds, so you can sort of see that when the intake velocities get too high there can be a good deal of friction in the intake piping. The choke line in a turbocharger is directly related to the speed of sound. At high loads it's not uncommon to see flow velocities of 80% or so the speed of sound in intake piping. So basically it's best to suit the intake piping to how much air you engine can actually flow.

However, in the EVO most aftermarket piping is 2.5 inches compared to the 2.25 inches stock, so it's really not that big a deal to upgrade for increased diameter, but it's ALWAYS good to have shorter piping with less bends, which is what they do.

I think there are some 3 in IC piping kits, such as AMS, but that's basically for a drag race car with lots of power and boost. It would be overkill for a road race car and useless for a street car.

I hope this all makes sense.

 

^^^^it sure does!!! Learning new things everyday!!!

 

You're the one that is claiming to be an engineer, so use your expertise to explain to us why generally excepted turbo design theory doesn't hold. You implied some sort of authority when you referenced your "engineering standpoint" which is funny given the context of your post and how far off the mark you are. As best I can tell, you're just another self proclaimed "internet expert" spreading misinformation.

So go ahead and explain your turbo system design theory to us.

 

you got me, not sure what to say

 

There is nothing to say. We all know you're wrong. You should not have said anything in the first place. Remember it is better to keep quite when one doesn't know of which they speak.

 

Well, I thought I would give you a chance (I knew you don't have facts or an answer but as I said I gave you a chance). One thing that will cause gas (air) to slow down is a sudden decrease in temperature. The other thing that can cause a decrease in flow velocity is rapid expansion and turbulence, like going from a small passage to a 6-inch pipe. A smaller-diameter pipe geometry will tend to keep the flow rate up, but it will also lose heat more quickly (less gas per linear inch of pipe). However, a large pipe will slow the velocity due to expansion. It’s all about compromises. The proper pipe size is going to be influenced by the flow rate (volume rate, which is related to RPM and engine displacement. Many factors to consider, Is this a street car, a race car, or something in between? Where will the engine spend most of its time? Idle, full throttle, part throttle?

 

So what does this have to do with back pressure and why you mistakenly think a turbo charged car needs back pressure. Everyone seems to realize you're mistaken but you. Nice try, but you're missing the point, again.

 

Well not sure what to tell you. You are a type of a guy that wont listen and wont read facts just like a 16 year old high school kid (you might be by the way).

It seems like you have your mind set so there is no reason for you to visit forums and share thoughts and knowledge.

Did you even read what I wrote above?

 

Az3ar,
Here is some true technical information from an actual turbo systems engineer, not to be confused with someone that thinks they are a turbo systems engineer.

Unlike your previous post, this has actual relevance to the back pressure question when it comes to turbo charged cars.

Again, argue the world is flat if you like, but you are still wrong. Hopefully after reading the excerpt below and all the other posts, you'll finally admit your wrong and we can stop this silliness.

FWIW, since you brought up age and background. I am 38 and have a degree from one of the top Universities in the world with a BS in Econ, a minor in philosophy and about 24 hours in the Engineering dept. None of this is relevant to the arguement at hand, but you brought it up.

The following excerpts are from Jay Kavanaugh, a turbosystems engineer at Garrett.

N/A cars: As most of you know, the design of turbo exhaust systems runs counter to exhaust design for n/a vehicles. N/A cars utilize exhaust velocity (not backpressure) in the collector to aid in scavenging other cylinders during the blowdown process. It just so happens that to get the appropriate velocity, you have to squeeze down the diameter of the discharge of the collector (aka the exhaust), which also induces backpressure. The backpressure is an undesirable byproduct of the desire to have a certain degree of exhaust velocity. Go too big, and you lose velocity and its associated beneficial scavenging effect. Too small and the backpressure skyrockets, more than offsetting any gain made by scavenging. There is a happy medium here.

For turbo cars, you throw all that out the window. You want the exhaust velocity to be high upstream of the turbine (i.e. in the header). You'll notice that primaries of turbo headers are smaller diameter than those of an n/a car of two-thirds the horsepower. The idea is to get the exhaust velocity up quickly, to get the turbo spooling as early as possible. Here, getting the boost up early is a much more effective way to torque than playing with tuned primary lengths and scavenging. The scavenging effects are small compared to what you'd get if you just got boost sooner instead. You have a turbo; you want boost. Just don't go so small on the header's primary diameter that you choke off the high end.

Downstream of the turbine (aka the turboback exhaust), you want the least backpressure possible. No ifs, ands, or buts. Stick a Hoover on the tailpipe if you can. The general rule of "larger is better" (to the point of diminishing returns) of turboback exhausts is valid. Here, the idea is to minimize the pressure downstream of the turbine in order to make the most effective use of the pressure that is being generated upstream of the turbine. Remember, a turbine operates via a pressure ratio. For a given turbine inlet pressure, you will get the highest pressure ratio across the turbine when you have the lowest possible discharge pressure. This means the turbine is able to do the most amount of work possible (i.e. drive the compressor and make boost) with the available inlet pressure.

Again, less pressure downstream of the turbine is goodness. This approach minimizes the time-to-boost (maximizes boost response) and will improve engine VE throughout the rev range.

As for 2.5" vs. 3.0", the "best" turboback exhaust depends on the amount of flow, or horsepower. At 250 hp, 2.5" is fine. Going to 3" at this power level won't get you much, if anything, other than a louder exhaust note. 300 hp and you're definitely suboptimal with 2.5". For 400-450 hp, even 3" is on the small side.”

"As for the geometry of the exhaust at the turbine discharge, the most optimal configuration would be a gradual increase in diameter from the turbine's exducer to the desired exhaust diameter-- via a straight conical diffuser of 7-12° included angle (to minimize flow separation and skin friction losses) mounted right at the turbine discharge. Many turbochargers found in diesels have this diffuser section cast right into the turbine housing. A hyperbolic increase in diameter (like a trumpet snorkus) is theoretically ideal but I've never seen one in use (and doubt it would be measurably superior to a straight diffuser). The wastegate flow would be via a completely divorced (separated from the main turbine discharge flow) dumptube. Due the realities of packaging, cost, and emissions compliance this config is rarely possible on street cars. You will, however, see this type of layout on dedicated race vehicles.

A large "bellmouth" config which combines the turbine discharge and wastegate flow (without a divider between the two) is certainly better than the compromised stock routing, but not as effective as the above.

If an integrated exhaust (non-divorced wastegate flow) is required, keep the wastegate flow separate from the main turbine discharge flow for ~12-18" before reintroducing it. This will minimize the impact on turbine efficiency-- the introduction of the wastegate flow disrupts the flow field of the main turbine discharge flow.

Necking the exhaust down to a suboptimal diameter is never a good idea, but if it is necessary, doing it further downstream is better than doing it close to the turbine discharge since it will minimize the exhaust's contribution to backpressure. Better yet: don't neck down the exhaust at all.

Also, the temperature of the exhaust coming out of a cat is higher than the inlet temperature, due to the exothermic oxidation of unburned hydrocarbons in the cat. So the total heat loss (and density increase) of the gases as it travels down the exhaust is not as prominent as it seems.

Another thing to keep in mind is that cylinder scavenging takes place where the flows from separate cylinders merge (i.e. in the collector). There is no such thing as cylinder scavenging downstream of the turbine, and hence, no reason to desire high exhaust velocity here. You will only introduce unwanted backpressure.

Other things you can do (in addition to choosing an appropriate diameter) to minimize exhaust backpressure in a turboback exhaust are: avoid crush-bent tubes (use mandrel bends); avoid tight-radius turns (keep it as straight as possible); avoid step changes in diameter; avoid "cheated" radii (cuts that are non-perpendicular); use a high flow cat; use a straight-thru perforated core muffler... etc.”

"Comparing the two bellmouth designs, I've never seen either one so I can only speculate. But based on your description, and assuming neither of them have a divider wall/tongue between the turbine discharge and wg dump, I'd venture that you'd be hard pressed to measure a difference between the two. The more gradual taper intuitively appears more desirable, but it's likely that it's beyond the point of diminishing returns. Either one sounds like it will improve the wastegate's discharge coefficient over the stock config, which will constitute the single biggest difference. This will allow more control over boost creep. Neither is as optimal as the divorced wastegate flow arrangement, however.

There's more to it, though-- if a larger bellmouth is excessively large right at the turbine discharge (a large step diameter increase), there will be an unrecoverable dump loss that will contribute to backpressure. This is why a gradual increase in diameter, like the conical diffuser mentioned earlier, is desirable at the turbine discharge.

As for primary lengths on turbo headers, it is advantageous to use equal-length primaries to time the arrival of the pulses at the turbine equally and to keep cylinder reversion balanced across all cylinders. This will improve boost response and the engine's VE. Equal-length is often difficult to achieve due to tight packaging, fabrication difficulty, and the desire to have runners of the shortest possible length.”

"Here's a worked example (simplified) of how larger exhausts help turbo cars:

Say you have a turbo operating at a turbine pressure ratio (aka expansion ratio) of 1.8:1. You have a small turboback exhaust that contributes, say, 10 psig backpressure at the turbine discharge at redline. The total backpressure seen by the engine (upstream of the turbine) in this case is:

(14.5 +10)*1.8 = 44.1 psia = 29.6 psig total backpressure

So here, the turbine contributed 19.6 psig of backpressure to the total.

Now you slap on a proper low-backpressure, big turboback exhaust. Same turbo, same boost, etc. You measure 3 psig backpressure at the turbine discharge. In this case the engine sees just 17 psig total backpressure! And the turbine's contribution to the total backpressure is reduced to 14 psig (note: this is 5.6 psig lower than its contribution in the "small turboback" case).

So in the end, the engine saw a reduction in backpressure of 12.6 psig when you swapped turbobacks in this example. This reduction in backpressure is where all the engine's VE gains come from.

This is why larger exhausts make such big gains on nearly all stock turbo cars-- the turbine compounds the downstream backpressure via its expansion ratio. This is also why bigger turbos make more power at a given boost level-- they improve engine VE by operating at lower turbine expansion ratios for a given boost level.

As you can see, the backpressure penalty of running a too-small exhaust (like 2.5" for 350 hp) will vary depending on the match. At a given power level, a smaller turbo will generally be operating at a higher turbine pressure ratio and so will actually make the engine more sensitive to the backpressure downstream of the turbine than a larger turbine/turbo would.

 

some good info there, thanks. I think you just said what i've tried to say a lot more clearly.

just a couple of things:
a.) the stock licp has a section about 1' long with around 1.5" diam. adding the turbo outlet (same diam) this makes the total length of the 1.5" pipe around 1.5'-2' long. I agree that the piping immediately connected to the turbo should be the same size as its exit, but why keep it there for all that length? Surely something like 5xdiameter then a long smooth taper would do it better?

b.) i'll read the back pressure myth in full soon, and i agree about the transient (see previous posts). however, in my experience, the same exhaust with/without the 'silencer bung' installed, the engine makes more torque lower down with the bung but less top end power. As we'd expect, it flows better at higher rates, but I think the slight restriction helps the engine in its midrange [note exhaust volume reamins constant]. I think it may be something to do with scavenging effects in the exh. mani. But like I said, i think the exhaust turbine creates more resistance to flow than you'd even want...

edit: just read the post above.... think i'm on the right track with scavenging in na cars...

 

There is always the opposed side of the theory. However, you copy and paste of the web not even knowing what are the contents or how tests were performed. I on the other hand love to use my brain to think and come up with things logically.

I stand behind my thoughts strong. I will believe what you say when you show me actual power gains from an IC pipe kit on a 100% stock EVO back to back runs.

Until then you have nothing against me but copy and paste.

Funny that some parts of the above post has points on my side

Did you even read it?